V - Index of

• RELIABILITY OF HITACHI IC MEMORIES
1. STRUCTURE
Ie memories are basically classified into bipolar
type and MOS type and utilized effectively by their
characteristics. The characteristic of bipolar memories
is high speed but small capacity, instead, MOS
memories have large capacity. There are also differences
in circuit design, layout pattern, degree of
integration, and manufacturing process. These
memories have been produced with the standardized
concept of design and inspection all through the
processes of designing, manufacturing and inspection.
IC memories are constituted by the unit patterns
called cells, which are integrated in high density.
The knowhows based on our experience have been
applied in every production stage. In addition, reliability
has been ensured using TEG (Test Element
Group) evaluation. Examples of cell circuits of
bipolar and MOS memories are shown in Table 1.
• Table 1 Basic Cell Circuit of IC Memories
Classification
Bipolar memory
(RAM)
Bipolar memory
(PROM)
NMOS memory
(DynamIc RAM)
NMOS memory
(PROM)
Application
Microcomputer
control use
Main memory of computer,
microcomputer memory
For
microcomputer
control
Example of
basic cell
circuit
Dies of IC memories are produced in various packages.
In this process of packaging, Hitachi has also
innovated new techniques and ensured to high level.
As packages for Ie memories, cerdip (glass-sealed)
packages and plastic packages are currently used.
Also such packages as Lee (Leadless Chip Carrier)
or SOP (Small Outline Package) have been developed
for high density packaging. Cerdip packages
sealed hermetically are suitable for equipment requiring
high reliability. Plastic packages are widely
applied to many kinds of equipment. Hitachi
plastic packages have been improved the reliability
level as highly as that of the hermetically sealed
packages. Table 2 shows the outlines of the Hitachi
packages.
• Table 2 IC Memory Package Outline
• Cerdip
.16 pin .18 Pin
.20 Pin .24 Pin
~HITACHI
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